A watch case which corresponds to the general definition given above has been described in patent document EP-A-No. 0 264 875. The case is formed preferably from a ceramic material as far as the caseband is concerned, and of steel in respect of the back cover. The back cover is secured to the caseband by means of four screw fastening points. To this end the caseband is provided with holes into which plugs are driven. Each plug is then pierced and internally threaded in taking as reference the inner bore of the caseband. This technique is here employed since it is unthinkable to fasten screws directly into the ceramic. It will be however readily appreciated that such arrangement is troublesome since it requires extra pieces, namely plugs which furthermore, when driven into the holes in the caseband, run a certain risk of bursting the ceramic. The operation of piercing the plugs also requires care, thus additional manufacturing time and greater costs.
To overcome these difficulties, the watch which is sold under the registered trademark "OMEGA ART" provides as a caseband the combination of a ceramic ring and a steel circle glued to the interior of the ring. The back cover is then fastened to the caseband by means of screws directly screwed into the steel circle. This solution avoids the plugs employed in the above cited patent document, but requires manufacture of a circle and the gluing of such circle to the interior of the ceramic ring which likewise is burdensome.
The patent document CH-A-No. 458 217 describes a watch case in which the back cover is hooked to the caseband on one hand by means of studs engaging in seatings provided in a first pair of lugs borne by the caseband and on the other hand by means of two pins which at the same time pass through the back cover and a second pair of lugs. Here the pins do not in any manner serve at the same time to attach the bracelet strands to the case.